4 Greenhouse Insulation Options

The interior of a greenhouse.

Greenhouse insulation is very important for reducing heating costs and increasing efficiency. If you live in a cold region and have to maintain a high temperature in your greenhouse, insulation can save you a lot of money over the colder months.

Before installing insulation in your greenhouse, it's important to understand the different insulating materials. Some of them reduce the amount of light that reaches the plants, so make sure you choose something that won't damage or kill the plants in your greenhouse.

1. Double Glazing

This is the most efficient way to insulate an entire greenhouse. If you plan to use this type of insulation, it should be installed as the greenhouse is being built. This is an expensive option, but it provides the greatest benefits.

2. Bubble Plastic

This is also very efficient. Bubble plastic is made up of double or triple skins of transparent plastic that contain air cells between them. This type of insulation lasts for three or four seasons before it needs to be replaced, but it’s still a cost-effective way to keep a greenhouse warm.

In comparison, one layer of plastic sheeting is much less efficient than bubble plastic at preventing heat loss. However, plastic sheeting is less expensive up front and won't cut out as much light. You can use plastic sheets in the winter to create a double glazing effect; just attach some to the structure with clips that fit into the frame.

3. Thermal Screens

This type of greenhouse insulation consists of clear plastic or translucent material, such as cross laminated fabric, which is attached to wires between the eaves. You pull the screens horizontally across the width of the greenhouse at night to conserve heat. They work by restricting the amount of heat that can rise above the eaves and trapping the warm air lower down in the greenhouse, around the plants. These screens are also handy for sectioning off a heated area on one end of the greenhouse, if you want to leave the rest of the greenhouse unheated.

4. Base Cladding

This option is installed on the floor level of glass greenhouses. It reduces heat loss by completely blocking out the lowest portion of the glass, where the walls meet the cold ground. You can also place polystyrene panels on the foot of the glass panes for added insulation. Just make sure that you remove them before the summer arrives.

The type of insulation you need depends on the plants you want to grow and the size of your greenhouse. Larger greenhouses may require a certain type of insulation to effectively trap heat in the structure. The type of insulation you choose will also depend on your budget and the environment you are trying to create.